Note: Descriptions are shown in the official language in which they were submitted.
CA 02652579 2008-11-17
WO 2007/141384 PCT/F12007/050321
1
METHOD AND ARRANGEMENT FOR IMPROVING SOIL AND/OR FOR LIFTING
STRUCTURES
BACKGROUND OF THE INVENTION
[0001] The invention relates to a method for improving soil and/or
for lifting ground-based structures, the method comprising providing the soil
or
structure with a hole, arranging into the hole an injection bar and an
expansion
element provided in connection therewith, and injecting a substance into the
expansion element.
[0002] The invention further relates to an arrangement for improving
soil and/or for lifting structures, the arrangement comprising an injection
bar to
be arranged into a hole and provided in connection with an expansion element,
a substance to be injected into the expansion element, and means for injecting
the substance into the expansion element.
[0003] Soil is improved e.g. in order to increase the bearing capacity
thereof or in order to fill empty spaces therein. Further, soil improvement is
necessary if vibrations transmitted via the soil are to be dampened or soil
liq-
uefaction taking place in connection with earthquakes is to be prevented. A
process of lifting structures, in turn, refers e.g. to lifting and stabilizing
buildings
or foundations for buildings or floors that are damaged, subsided or
dislocated.
Furthermore, the process of lifting structures comprises lifting and
stabilizing
subsided paved roads or fields, such as concrete and asphalt roads or run-
ways.
[0004] Deterioration of soil or subsidence of structures may be
caused e.g. by poorly consolidated soil, water-induced erosion, inappropriate
soil type during construction, deterioration of frictional forces in the soil,
or
variations in temperature or humidity conditions. Further, soil deterioration
may
be caused by changes in conditions due to mechanical damage, such as
breakage of water or sewer pipes. Moreover, soil conditions may change due
to the influence of dynamic forces.
[0005] In order to improve the soil, soil having a poor bearing ca-
pacity is replaced by a substance having a better bearing capacity. Such a
process called mass exchange is extremely laborious and expensive. Further,
piling techniques, such as friction piles which, through friction, are
supported
by the soil, or base piles which rest on the hard bottom layer, are used.
Piling
requires heavy and complex equipment, which subjects the environment to
CA 02652579 2008-11-17
WO 2007/141384 PCT/F12007/050321
2
noise and further disturbance. Since the piling is fastened to a structure, it
sub-
jects the structure to point loads when the structure is supported by piles,
and
not by the soil.
[0006] EP 0 851 064 discloses a solution for improving the bearing
capacity of soil. In the solution, the soil is provided with holes into which
a sub-
stance which expands as a consequence of a chemical reaction is injected.
EP 1 314 824 discloses a similar solution wherein a substance is used for pro-
ducing a pressure of more than 500 kPa. In practice, it has been noticed that
in
these solutions, the only way to determine a dose to be injected is to monitor
the surface of the ground or the height level of a building, and stop
injecting
when a reaction in these aspects is observed. When these solutions are used
in connection with porous and soft soils in particular, the procedures of
dosing
the substance to be injected appropriately and directing the expansion force
correctly as well as keeping the substance in a desired place present very
challenging tasks.
[0007] JP 7 018 651 discloses a solution wherein expanding bag
bodies are arranged into holes drilled into the soil. A hardening agent is
pumped into the bags with a high pressure. Due to the usage of a high hydrau-
lic pressure, the devices used are complex and, for example, valves that are
failure-sensitive in difficult conditions are required. Furthermore, in soft
soil, it is
uncertain that the bag stays in place, so it is very difficult to condense a
portion
of soft soil by means of this solution. Still further, if a bag is broken, the
con-
densing process gets totally out of control. JP 10 195 860 discloses a similar
solution wherein a flexible bag is used. This solution also suffers from prob-
lems similar to those disclosed above. JP 2003 105 745 discloses a solution
wherein plastic mortar is injected into soil or into a bag arranged in the
soil.
The above-disclosed problems are present also in this solution when a sub-
stance is injected into a bag.
[0008] JP 9 158 235 discloses a solution for correcting inclination of
a building. The solution comprises drilling a hole which extends under the
foundations of the building. Here, under the foundations, a flexible bag is ar-
ranged into which water and a consolidating substance are conveyed through
separate pipes. The aim is to lift the building through filling the bag. This
solu-
tion also requires the usage of an extremely high hydraulic pressure,
resulting
in complex and failure-sensitive equipment. The equipment also includes a
plurality of pipes, which adds to its complexity. Furthermore, if a bag is
broken
CA 02652579 2013-11-26
3
while in use, the structure may collapse at the particular bag, so the method
is ex-
tremely risky.
BRIEF DESCRIPTION OF THE INVENTION
[0009] The present invention provides a novel method and arrangement
for condensing, filling or replacing soil and/or for lifting structures.
[0010] Accordingly, the present invention provides a method for at
least one of condensing, filling and replacing soil, and for lifting
structures, the
method comprising providing the soil or structure with a hole, arranging into
the
hole an injection bar and an expansion element provided in connection
therewith,
and injecting a substance into the expansion element, wherein the substance ex-
pands as a consequence of a chemical reaction, so that a force pressing the ex-
pansion element against the soil is generated mainly by the chemical reaction.
[0011] The present invention also provides an arrangement for at least
one of condensing, filling and replacing soil and for lifting structures, the
arrange-
ment comprising an injection bar to be arranged into a hole and provided in
con-
nection with an expansion element, a substance to be injected into the
expansion
element, and means for injecting the substance into the expansion element,
wherein the substance to be injected into the expansion element is a substance
which expands as a consequence of a chemical reaction, so that a force
pressing
the expansion element against the soil is generated mainly by the chemical
reac-
tion.
[0012] An idea of the invention is that a hole is formed into the soil or
structure, and an injection bar accompanied by a fillable expansion element is
ar-
ranged into the hole. A substance which expands as a consequence of a chemical
reaction is injected into the expansion element. The expansion element filled
with
the reacted substance condenses, fills or replaces surrounding soil or lifts
as well
as stabilizes ground-based structures. A force pressing the expansion element
against the soil is generated by the chemical reaction, which expands the sub-
stance injected into the expansion element. The substance also hardens very
CA 02652579 2013-11-26
3a
quickly, so no valves to keep the substance within the expansion element are
nec-
essary in the solution. The expansion element enables the expanding substance
to be placed in a controlled manner at a desired point. Thus, the localization
of
expansion pressure is completely controlled. Also e.g. in loose soil, the
substance
may be provided with a high compression strength. The injection bar can be ar-
ranged into a very small hole, so no extensive excavations are necessary.
Since
the substance hardens very quickly, no substantial extensive and uncontrolled
movements of the substance occur should the expansion element be broken. Fur-
ther, when used for lifting structures, breakage of the expansion element does
not
substantially damage the strength of the foundations of a building. All in
all, the
machines and devices to be used in the solution are quite small and simple
and,
what is more, the solution is excellent as far as work safety is concerned.
CA 02652579 2008-11-17
WO 2007/141384 PCT/F12007/050321
4
[0013] An idea of an embodiment is that the injection bar is left in its
place in the soil to anchor the expansion element and the substance expanded
therein in place. This ensures that the expansion element stays at a desired
point also in soft soil.
[0014] An idea of a second embodiment is that the injection bar is
arranged to penetrate through the expansion element and, on its sides, the
injection bar is provided with openings for the substance to be injected into
the
expansion element so as to allow the substance to enter the expansion ele-
ment. Such a solution is simple, functional, and effective.
[0015] An idea of a third embodiment is that the expansion element
is substantially impermeable to air such that the expansion element is
provided
with an airtight expansion space therein to enable the expansion reaction to
be
implemented in a controlled manner.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The invention is described in closer detail in the accompany-
ing drawings, in which
[0017] Figure 1 schematically shows a cross-sectional side view of
an injection bar and an expansion element,
[0018] Figure 2 schematically shows the bar and the expansion
element according to Figure 1 arranged in place and with an injection sub-
stance having already reacted,
[0019] Figure 3 schematically shows a way of improving the bearing
capacity of soil,
[0020] Figure 4a schematically shows a cross-sectional side view of
a second injection bar and expansion element,
[0021] Figure 4b shows the solution of Figure 4a with the expansion
element filled up,
[0022] Figure 5 schematically shows a cross-sectional side view of
an injection bar and an expansion element arranged inside a protective pipe,
[0023] Figure 6 schematically shows injection bars and expansion
elements arranged in connection with a larger pipe,
[0024] Figure 7 schematically shows, in the manner of Figure 6, in-
jection bars and expansion elements arranged in connection with a larger pipe,
and
[0025] Figure 8 schematically shows how a structure is lifted.
CA 02652579 2008-11-17
WO 2007/141384 PCT/F12007/050321
[0026] For the sake of clarity, the figures show some embodiments
of the invention in a simplified manner. In the figures, like reference
numerals
identify like elements.
DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION
[0027] Figure 1 shows an injection rod or injection bar 1. In the em-
bodiment shown in Figure 1, an upper end of the injection bar 1 is hollow
while
a lower end thereof is closed. The outer diameter of the injection bar 1 may
vary e.g. between 3 and 200 mm. The length of the injection bar 1 may vary
e.g. between 0.5 and 100 m. The injection bar 1 may be made e.g. of metal,
such as steel.
[0028] The injection bar 1 may also be made of another material,
such as plastics, e.g. polyethylene PE. Further, the injection bar 1 does not
necessarily have to be stiff. The injection bar 1 may thus be e.g. a hose or a
pipe made of plastics.
[0029] A fillable expansion element 2 is arranged around the injec-
tion bar 1. The expansion element 2 is preferably manufactured from a mate-
rial which is impermeable to air and substantially inextensible. An example of
such a material is geotextile. Further, another flexible and strong material
may
be used.
[0030] The expansion element may be made of plastic, such as
polyester or polypropylene or artificial or natural fibre. It may also be made
of
rubber or another elastomer. A wall of the expansion element may be perme-
able or impermeable to air. The wall of the expansion element 2 may also be
flexible or inflexible. The wall of the expansion element 2 may also be
provided
with metal reinforcement material or glass fibre or another suitable reinforce-
ment. The expansion element may be either seamless or with seams. A seam
may be provided e.g. by sewing, gluing, using a fastening element, riveting,
welding, soldering, fusing or by another mechanical, chemical, thermal or elec-
trical method or a combination thereof.
[0031] The thickness of a wall of the expansion element 2 may vary
e.g. between 0.02 and 5 mm, depending on the material, size of the expansion
element 2, expansion pressure, etc. The injection bar 1 is preferably arranged
through the expansion element 2 so that the expansion element 2 is fastened
to the injection bar 1 e.g. in the manner shown in Figure 1 by means of a
lower
fastener 3a and an upper fastener 3b. Prior to arranging the injection bar 1
into
CA 02652579 2008-11-17
WO 2007/141384 PCT/F12007/050321
6
the soil, the expansion element 2 is wound or folded against the injection bar
1. When the expansion element 2 is completely filled up with a solid sub-
stance, its outer diameter may vary e.g. between 20 cm and 5 m. Similarly, the
length of the expansion element 2, i.e. the distance between the lower
fastener
3a and the upper fastener 3b, may vary e.g. between 20 cm and 100 m.
[0032] The expansion element 2 may be e.g. of the shape of a cy-
lindrical sleeve. Furthermore, the upper and lower ends of expansion element
2 may be narrower while the diameter of the middle part thereof may be larger.
The external appearance of the expansion element 2 prior to being injected
with a substance is irrelevant. After the substance has reacted inside the ex-
pansion element, the expansion element reaches its final appearance.
[0033] The lower fastener 3a and the upper fastener 3b may be e.g.
hose clamps. Further, the fasteners may be e.g. metal sleeves provided by
cutting off a piece of pipe. A metal sleeve may be fastened in place by means
of pressing.
[0034] The lower fastener 3a or the upper fastener 3b or both may
also be made movable, in which case when the expansion element 2 is being
filled, they slide into a suitable place. In comparison with stationary
fasteners,
this solution has an advantage which enables distortion and consequently
even breakage of the injection bar to be avoided. For instance, the lower fas-
tener may be made movable by providing a lower end of the injection bar with
a solid bar and arranging a movable sleeve thereon. A wall of the expansion
element is arranged on the movable sleeve and a fastening sleeve is arranged
around it, the wall of the expansion element thus residing fixedly between the
fastening sleeve and the movable sleeve. When the movable sleeve is thus
allowed to slide along the surface of the bar, the fastener moves as the expan-
sion element is being filled up.
[0035] Figure 1 further schematically shows an injection apparatus
4, which includes containers wherein a substance to be injected into the ex-
pansion element 2 is stored, and means for conveying the substance from
such a container into the hollow upper part of the injection bar 1. The
structure
of the means may be very simple and light, since they do not have to generate
any pressure to expand the expansion element 2 in the soil. The means gen-
erate pressure to enable the substance to be injected to be conveyed to the
expansion element through hoses and pipes, but they do not generate the ac-
tual expansion pressure but the expansion pressure is generated inside the
CA 02652579 2008-11-17
WO 2007/141384 PCT/F12007/050321
7
expansion element 2 chemically. The injection apparatus 4 is not discussed in
detail herein since its structure and operation are clear to those skilled in
the
art.
[0036] The injectable substance flows as shown by the arrows in
Figure 1, through the hollow upper end of the injection bar 1 and via openings
provided in the side of the injection bar 1 into the expansion element 2. A
chemical reaction takes place in the expansion element 2 such that the sub-
stance expands inside the expansion element 2.
[0037] The injection bar may also consist of an outer rigid pipe and
a hose or pipe arranged thereinside. The inner pipe is movable back and forth
inside the outer pipe and, when necessary, also rotatable. The substance to be
injected flows through the inner pipe and exits at its lower end and further
through openings provided in a side of the outer pipe to the expansion ele-
ment. While the expansion element is being filled up, the inner pipe is being
pulled out of the inside of the pipe. Consequently, when the expansion element
is being filled, the substance to be injected flows into the expansion element
from a point located closer and closer to an end of the injection bar facing
the
injection apparatus. The inner pipe may be pulled out of the outer pipe con-
tinuously and uniformly or stepwise. Furthermore, such a solution enables a
desired spot in the expansion element to be provided with the substance to be
injected. For instance, the inner pipe may quite extensively be pulled out of
the
outer pipe and a substance may be injected into an upper part of the expan-
sion element and a reaction and solidification of the substance may be awaited
and, subsequently, the inner pipe may be pushed back inside and inject the
substance lower into the expansion element. Such a solution enables the ex-
pansion element to be expanded also e.g. at a place which contains a locally
dense soil.
[0038] Figure 2 shows a situation wherein the injection bar 1 has
been arranged in the soil and the substance inside the expansion element 2
has already reacted, expanding the expansion element 2.
[0039] First, the bearing capacity of the soil and other necessary
soil conditions are measured using an appropriate method. The bearing capac-
ity of the soil may be measured by means of e.g. a penetrometer, or another
geological or geotechnical examination method. The measurements and ex-
aminations enable calculations relating to the soil to be made. On the basis
of
the measurements, examinations and calculations, the points to be processed
CA 02652579 2008-11-17
WO 2007/141384 PCT/F12007/050321
8
may be located in the soil. Such localization of a site to be processed
depends
on the soil conditions. The aim is to achieve a clear picture of the soil
vertically,
horizontally as well as laterally in order to process the soil accurately. On
the
basis of the result obtained, an injection bar 1 is manufactured and an expan-
sion element 2 is fastened thereto. The height and volume of the expansion
element 2 and the number of the expansion elements 2 are selected on the
basis of the soil conditions. When the solution is used for lifting
structures, the
size of the expansion element is also naturally affected by the size, weight
and
lifting need of the structure being processed. A hole 6 is drilled into the
soil.
The injection bar 1 equipped with the expansion element 2 is arranged in the
hole 6. An expanding substance is injected into the expansion element 2. The
expanding material may be e.g. a polymer, expanding resin or an organically
incrystallizable, chemically expanding multicomponent substance.
[0040] The expanding substance may be e.g. a mixture mainly con-
taining two components. In such a case, a first component may mainly contain
e.g. polyetherpolyol and/or polyesterpolyol. A second component may contain
e.g. isocyanate. The volumetric ratios of the first and the second components
may vary e.g. between 0.8 to 1,2: 0.8 to 1.8. The expanding substance may
also contain catalysts and water and, when desired, also other components,
such as silica, stone dust, fibre reinforcements and other possible additives
and/or auxiliaries and/or fillers.
[0041] The injectable substance is preferably a substance which
starts to react by expanding within 0.5 to 3600 seconds after having been in-
jected into the expansion element 2. In an embodiment, the substance starts to
react after more than 20 or more than 25 seconds since the injection, whereby
the expansion element 2 is filled up evenly, and with a very small risk of
break-
age. Furthermore, in an embodiment, the substance starts to react after less
than 50 seconds after the injection, which makes the process easy to manage.
[0042] The substance expands e.g. 1 to 120 times its original vol-
ume. The expansion factor of the substance, i.e. the volume of the substance
at the end of the reaction as compared with the volume of the substance at the
beginning of the reaction, may be e.g. of the order of 1.1 to 120. Preferably,
the substance is arranged to expand 1.5 to 20 times its original volume.
[0043] The expanding material condenses, fills or replaces sur-
rounding soil, depending on the type or density of the surrounding soil. The
replacement takes place by pushing the existing soil aside. The soil may be
CA 02652579 2008-11-17
WO 2007/141384 PCT/F12007/050321
9
compressible or incompressible. The final result obtained may be measured
using a soil measurement method. In this case, too, e.g. a penetrometer or
another geotechnical measuring device may be used for carrying out the
measurements.
[0044] Preferably, the substance reaches a very high compression
strength very quickly. The length of the time during which the substance
reaches a high compression strength depends on many different features,
such as the amount of the substance, volume of the expansion element, reac-
tion rate of the substance, prevalent temperature conditions, surrounding
soil,
and the load the soil is subjected to. The substance may reach e.g. 80 to 90%
of its final compression strength within about 10 to 15 minutes. Then, e.g. in
connection with lifting structures, the expanding substance is capable of re-
ceiving loads, and no serious adverse effects are caused even if the expansion
element 2 is broken. The amount of the substance to be injected into the ex-
pansion element 2 depends on the volume of the expansion element 2 as well
as on the determined bearing capacity of the soil and, further, on the desired
effect. The procedure of determining the amount of the substance requires an
expansion profile for the injectable substance, i.e. data about how much the
substance expands, how long it takes, and the amount of force it causes.
Thus, the amount is affected by the expansion profile. Next, the way in which
it
is utilized with respect to the space available, i.e. the volume of the
expansion
element 2, is determined. In a lifting situation, for example, it is not
always
necessary to fill the expansion element 2 to the maximum.
[0045] The final compression strength of the substance may be de-
termined in a controlled manner prior to injecting. In such a case, the final
compression strength of the substance is thus determined in advance, i.e.
prior
to injecting, on the basis of the resistance of the soil and the space
available,
i.e. the volume of the expansion element 2.
[0046] The pressure produced by the substance being used, i.e. the
force per surface area, may vary e.g. between 1 millibar and 800 bar. The
compression strength of the substance may vary e.g. between 1 millibar and
3000 bar. The final density of the substance may vary e.g. between 10 to 1200
kg/m3.
[0047] The expansion element 2 may thus be e.g. a cylindrical
sleeve or another similar structure defined by a wall made of a flexible mate-
rial. The injection bar 1 does not necessarily have to penetrate through the
ex-
CA 02652579 2008-11-17
WO 2007/141384 PCT/F12007/050321
pansion element 2 but the expansion element 2 may be fastened e.g. to an
end of the injection bar 1. In such a case, the expansion element 2 may be
e.g.
a bag or a sack, and fastened to the injection bar 1 at its one point only
such
that the substance flows through the hollow injection bar 1, from its end, to
the
expansion element 2.
[0048] If the soil is suitably soft and the injection bar 1 is sufficiently
stiff, a hole 6 may be provided by pushing the injection bar 1 into the soil.
In
such a case, the procedures of providing a hole and arranging the injection
bar
1 into the hole thus take place simultaneously. Furthermore, prior to pushing
the injection bar 1 into the soil, a hole with a diameter smaller than the
outer
diameter of the injection bar may be provided therefor. Most typically,
however,
a hole with a diameter slightly larger than the outer diameter of the
injection
bar 1 is drilled for the injection bar 1. In such a case, the hole 6 also
easily ac-
commodates an expansion element 2 folded around the injection bar.
[0049] In order to reduce the size of a hole required by the expan-
sion element 2, the expansion element is preferably provided with an outer
diameter which is as small as possible. The expansion element is folded on the
outside of the injection bar 1 and preferably reduced in size e.g. by a press
so
as to lie as tightly as possible against the injection bar 1. The outer
diameter of
the expansion element may also be reduced utilizing heat, pressurized air,
moisture, suction and/or pressure e.g. by roll-calendering. It may be further
ensured that the expansion element 2 stays tightly against the injection bar 1
by arranging a plastic film on top of the element. The plastic film may be ar-
ranged on top of the expansion element 2 e.g. by sliding or winding.
[0050] It is possible to let the plastic film to remain on the expansion
element 2 such that the material to be injected is injected inside the plastic
film.
This provides the feature that the injected material must have a compression
strength high enough before it tears the film and expands the expansion ele-
ment. The film can be provided with a tearing line, such as a perforation,
whereby the tearing force needed can be determined accurately. Further the
tearing force can be formed to be different at different parts of the film.
Using
the film on the expansion element 2 together with an injection bar comprising
an outer pipe and an inner pipe provides the possibility to expand the expan-
sion element 2 at a desired spot.
[0051] Soil examination may reveal that a cavity exists in the soil
that should be filled. The injection bar 1 is very easy to arrange in the
cavity,
CA 02652579 2008-11-17
WO 2007/141384 PCT/F12007/050321
11
e.g. the injection bar 1 according to Figure 1, such that it penetrates
through
the cavity. The expansion element 2 then sets at the particular cavity. The ex-
panding substance inside the expansion element 2 fills the cavity and the ex-
pansion element 2 prevents the expanding substance from creeping out of the
cavity.
[0052] If desired, the procedure may include removing the injection
bar 1 from the soil, so that only the expansion element 2 remains to fill the
de-
sired spot. The injection bar 1 may, however, also be left in its place to
anchor
the expansion element 2 and the substance therein tightly in place.
[0053] Figure 2 shows a situation wherein a soil layer 7b having a
lower bearing capacity resides between an upper bearing soil layer 7a and a
lower bearing soil layer 7c. The expansion element 2 is dimensioned to fill
the
soil layer 7b having the lower bearing capacity. The upper and lower ends of
the injection bar 1, in turn, become tightly anchored in the bearing soil
layers
7a and 7c. In such a case, the expansion element 2 and the substance therein
stay in place, even if the soil layer having the lower bearing capacity were
ex-
tremely soft.
[0054] Figure 3 schematically shows how it is possible to improve a
soil layer 7b having a lower bearing capacity. A plurality of injection bars 1
equipped with an expansion element 2 has been arranged side by side. If nec-
essary, a plurality of expansion elements 2 may also be arranged on top of one
another, either by using one injection bar 1 per a plurality of expansion ele-
ments or by using in connection with each expansion element 2 an injection
bar 1 of its own. In this manner, the expansion elements 2 containing the re-
acted substance may be used for supporting the upper soil layer 7a. This en-
ables the bearing capacity of the soil to be improved extensively. The soil
layer
7b having the lower bearing capacity is not necessarily condensed, but the
solution of Figure 3, for example, enables the total bearing capacity to be im-
proved in any case.
[0055] In the accompanying drawings, the injection bar 1 is shown
to be accompanied by one expansion element 2 but, if desired, two or more
expansion elements 2 may be arranged in connection with one injection bar 1
to be filled with an expanding substance.
[0056] As shown in Figure 4a, the expansion element 2 does not
necessarily have to be arranged outside the injection bar 1. If the inner
diame-
ter of the injection bar 1 is sufficient, e.g. at least 50 mm, the expansion
el e-
CA 02652579 2008-11-17
WO 2007/141384 PCT/F12007/050321
12
ment 2 may be folded inside the injection bar 1. In such cases, the expansion
element 2 may be e.g. a bag or a sack which at its mouth part is fastened to
the lower end of the injection bar 1. When a substance is then injected into
the
expansion element 2, the substance pushes the expansion element 2 out of
the injection bar 1, as shown in Figure 4b.
[0057] As shown in Figure 5, a protective pipe 8 may be arranged
outside the injection bar 1 and the expansion element 2. The injection bar 1
and the expansion element 2 are forced into the soil by means of the
protective
pipe 8. The protective pipe 8 is pulled out before injecting the substance
into
the expansion element 2.
[0058] Figure 6 shows a structure wherein a plurality of expansion
elements 2 are arranged on the walls of a pipe 9 having a larger diameter.
Hoses for injecting a substance into the expansion elements 2 serve as injec-
tion bars 1. The hoses may be arranged inside the pipe 9 having a larger di-
ameter.
[0059] In the embodiment of Figure 7, the expansion elements 2 are
arranged outside a larger pipe 9. In the embodiment of Figure 7, two expan-
sion elements 2 have been arranged on top of one another and fastened by
means of fasteners 3a, 3b, and 3c. Also in this embodiment, hoses serving as
injection bars 1 are arranged inside the pipe 9 having a larger diameter.
[0060] Figure 8 shows a basic principle for lifting a ground-based
structure 10. The amount to be injected during lifting may be determined by
observing the vertical transition of the ground-based structure. Observing the
vertical transition may mean observing when the structure starts moving, or
observing when the structure has risen a desired distance. In Figure 8, the
ground-based structure 10 is designated by a road pavement. When lifting a
ground-based structure, the expansion element is at least partly supported by
the soil.
[0061] In some cases the features disclosed in the present applica-
tion may be used as such, irrespective of other features. On the other hand,
the features set forth in the present application may, when necessary, be com-
bined in order to provide different combinations.
[0062] The drawings and the related description are only intended
to illustrate the idea of the invention. In its details, the invention may
vary within
the scope of the claims.
CA 02652579 2008-11-17
WO 2007/141384 PCT/F12007/050321
13
[0063] In addition to improving soil, the disclosed solution may thus
be used for lifting ground-based structures, whereby e.g. damaged, subsided
or dislocated buildings or foundations or floors of structures are lifted and
stabi-
lized. Further, the solution may be used for lifting and stabilizing subsided
paved roads, for instance. An empty space beneath a structure may necessi-
tate a lifting process. In such a case, a hole may be drilled through the
struc-
ture and arrange an injection bar therethrough such that an expansion element
sets in the empty space. Next, the expansion element is filled as described
above such that the chemical expansion reaction taking place inside the ex-
pansion element fills the empty space. The injection bar 1 may be arranged
either directly downwards or obliquely downwards. Moreover, the injection bar
1 may also be arranged horizontally when processing e.g. the soil in embank-
ments. The solution may also be used for lifting and fixing abutments or ap-
proaches for bridges.
[0064] Furthermore, the disclosed solution may be used for provid-
ing a dam wall to prevent water from passing in the soil or excavation. Simi-
larly, the solution may be used for supporting walls of excavations. A dam
wall
or an excavation support may be provided by arranging expansion elements
side by side. An expanding substance may be injected outside the expansion
elements between the elements in order to attach the expansion elements to
one another.
[0065] Preferably, the amount of a substance to be injected into an
expansion element is thus determined prior to injecting, on the basis of soil
characteristics, volume of the expansion element and the desired effect. The
amount to be injected may also be determined by monitoring the expansion
element being filled. Such monitoring may be carried out by means of e.g. an
earth radar. In such a case, the material of the expansion element, for in-
stance, may be selected such it can be seen in the radar. For example, the
wall of the expansion element may be provided with metal fibers to make the
expansion element clearly visible in the radar. Furthermore, the amount of the
substance to be injected may be determined by monitoring the consistency of
the soil or the density of the filling material. A further solution is to
arrange a
pressure sensor inside the expansion element or in the wall of the expansion
element, inside or outside the wall. The pressure sensor may also be arranged
in the soil, in the vicinity of the expansion element, i.e. outside the
expansion
CA 02652579 2008-11-17
WO 2007/141384 PCT/F12007/050321
14
element. Further, the size of the expansion element may be monitored by
means of a thermographic camera.
[0066] The procedure of monitoring the expansion element being
filled in order to determine the amount to be injected may also be carried out
such that the substance is injected into the expansion element until the expan-
sion element breaks as the substance expands without, however, the structure
under repair being damaged. The breakage of the expansion element is ob-
served on the basis of sound or shock. Before breaking, however, the expan-
sion element 2 has restricted the substance to remain at a particular point.
The
substance hardens so quickly that even if the expansion element is broken, it
does not creep a long distance away from the injection site, not even in soft
soil.
[0067] Preferably, the wall of the expansion element is manufac-
tured from an airtight material. In such a case, the expansion element may be
oxygen-free. When the inside of the expansion element is oxygen-free, the
reaction of the substance can be managed extremely well. On the other hand,
no need exists for the expansion element to be completely oxygen-free on the
inside. However, an oxygen-free wall ensures that substantially no oxygen en-
ters the expansion element from outside. When the wall of the expansion ele-
ment prevents additional oxygen supply, the expansion reaction of the sub-
stance can thus be kept under control.
[0068] No need necessarily exists for the wall of the expansion ele-
ment to remain intact after the expansion reaction. At the beginning of the ex-
pansion reaction, however, the expansion element restricts the expanding
substance to remain within the desired area, so that even in a porous soil,
the
substance does not start creeping. If the substance reacts, i.e. hardens,
quickly enough, no uncontrollable creeping of the substance in the soil occurs
even if the wall of the expansion element is broken.
